Method for detecting failure when installing input-output controller

ABSTRACT

A failure detection method enabling the detection of I/O bus failure and address parity error when installing I/O controllers connected to a system bus in a computer system, and also enabling failure location when installing units in slave/master relationships (e.g. SCSI controller and disk storage units) and when installing an additional slave in a computer system, thus improving the reliability of the system. The failure detection method comprises the steps of executing an instruction which involves providing I/O bus access to a memory to be used by an I/O controller after installed, determining that there is no failure when predetermined results are obtained with the instruction, and installing the I/O controller in the system. When the I/O controller has slave/master relationships with a plurality of slave units, the failure detection method further comprises the steps of detecting a failure in the slave units on the occasion of the installation, and notifying the host processor of the slave unit having the failure.

FIELD OF THE INVENTION

[0001] The present invention relates to a system including aninput-output controller such as a SCSI (Small Computer System Interface)controller, etc. and a method for detecting a failure when installing aninput-output controller.

BACKGROUND OF THE INVENTION

[0002] A computer system generally comprises a number of input-output(I/O) controllers such as a LAN controller and a SCSI controller inaddition to a control section (hereinafter referred to as a processorunit) including a processor that takes a central part in the system anda memory. The processor unit is connected to other units via systembuses. There have been disclosed some techniques for fault detectionconcerned with the system bus in Japanese Patent Applications laid openNo. HEI4-8147, laid open No. HEI7-168727, and laid open No. HEI8-263328.

[0003] A SCSI port is a standard interface for connecting the peripheralequipment such as a HDD (Hard Disk Drive) with the processor unit. Withthe SCSI port, a SCSI controller is used as an I/O controller to be ahost for communicating with a magnetic disk and the like. Techniquesinvolved with the SCSI controller have been disclosed, for example, inJapanese Patent Applications laid open No. HEI11-203239 and laid openNo. HEI11-110138.

[0004] Generally, in a conventional system, I/O controllers like theSCSI controller are installed in the system when the operation of theprocessor unit starts. At a restart of the processor unit or whenexecuting an instruction from a system maintainer to install an I/Ocontroller, only a part of memory area related to the operation of theI/O controller is used and installation processing is simply carried outduring the process of the installation. After completion of theinstallation, necessary parts of memory area are selectively used forexecuting respective instructions each time when I/O access occurs inoperation.

[0005] In the following, a description will be given of problems in theabove-mentioned conventional techniques and systems.

[0006] The first problem is that an I/O bus access fault which occurswhile using an I/O controller has an impact on the whole processorsystem, thus causing a system failure. This is because a fault cannot belocated when the fault occurs in the I/O bus access from the I/Ocontroller to the memory.

[0007] The second problem is that the I/O controller which has causedthe failure can be reinstalled when restarting the processor. This isbecause normal operation is performed at the stage of installationprocessing since only sectional I/O bus accesses may occur wheninstalling the I/O controller.

[0008] The third problem is that in the case where an I/O controllerhaving slave/master relationships with plural devices (slave devices),for example, the SCSI controller and disk storage units are installedand one of the slave devices has a failure, the slave device with thefailure cannot be specified.

[0009] Besides, in a system adopting a disk array, etc., there is a casewhere an additional disk storage unit is installed in the active systemin which the SCSI controller and a disk storage unit #A have beenalready installed. When a SCSI controller failure is detected on suchoccasion and failure recovery is performed for the SCSI controller whilethe disk storage unit #A is in use, accessing to the disk storage unit#A is interrupted, which affects a software or program running on thesystem.

SUMMARY OF THE INVENTION

[0010] It is therefore an object of the present invention to provide afailure detection method enabling the detection of I/O bus failure andaddress parity error when installing I/O controllers such as a SCSIcontroller, etc. connected to a system bus in a computer system, thusimproving the reliability of the system.

[0011] It is another object of the present invention to provide afailure detection method enabling failure location when installing unitsin slave/master relationships (e.g. SCSI controller and disk storageunits) and also when installing an additional slave in a computersystem, thus improving the reliability of the system.

[0012] In accordance with the first aspect of the present invention, toachieve the above objects, there is provided a failure detection methodfor detecting a failure at a time when installing an I/O controller in acomputer system, comprising the steps of executing an instruction whichinvolves providing I/O bus access to a memory to be used by the I/Ocontroller after installed; determining that there is no failure whenpredetermined results are obtained with the instruction; and installingthe I/O controller in the system.

[0013] In accordance with the second aspect of the present invention,there is provided a failure detection method for detecting a failure ata time when installing an I/O controller in a computer system,comprising the steps of: executing an instruction which involvesproviding I/O bus access to a memory to be used by the I/O controllerafter installed; determining that there is no failure when predeterminedresults are obtained with the instruction and installing the I/Ocontroller in the system; and notifying a host processor that there is afailure in the I/O controller when predetermined results are notobtained with the instruction so that the host processor can specify theI/O controller with the failure.

[0014] In accordance with the third aspect of the present invention, inthe first or second aspect, the failure detection method furthercomprises the steps of executing a micro diagnostic program stored inthe 1/O controller; and installing the I/O controller in the system whenit is verified that there is no failure by the micro diagnostic program.

[0015] In accordance with the fourth aspect of the present invention, inone of the first to third aspects, the I/O controller has slave/masterrelationships with a plurality of slave units, and the failure detectionmethod further comprises the steps of; detecting a failure in therespective slave units when installing the I/O controller; and when afailure is found in any of the slave units, notifying the host processorof the slave unit having the failure.

[0016] In accordance with the fifth aspect of the present invention, inthe fourth aspect, the failure detection method further comprises thesteps of executing an instruction which involves providing I/O busaccess to a memory to be used by the respective slave units afterinstalled; determining that there is no failure when predeterminedresults are obtained with the instruction; and notifying the hostprocessor of the slave unit having a failure when predetermined resultsare not obtained with the instruction.

[0017] In accordance with the sixth aspect of the present invention, inone of the first to fifth aspects, the I/O controller is a SCSIcontroller.

[0018] In accordance with the seventh aspect of the present invention,in one of the first to sixth aspects, a system maintainer is informed asto the result of the installation of the I/O controller.

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The objects and features of the present invention will becomemore apparent from the consideration of the following detaileddescription taken in conjunction with the accompanying drawings inwhich:

[0020]FIG. 1 is a block diagram showing the configuration of the mainpart of a preferred computer system for illustrating an application ofthe present invention;

[0021]FIG. 2 is a flowchart showing the operation process according tothe first embodiment of the present invention;

[0022]FIG. 3 is a block diagram showing the configuration of the mainpart of another preferred computer system for illustrating anapplication of the present invention; and

[0023]FIG. 4 is a flowchart showing the operation process according tothe second embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] Referring now to the drawings, a description of preferredembodiments of the present invention will be given in detail.

[0025]FIG. 1 is a block diagram showing the configuration of the mainpart of a preferred computer system for the application of the firstembodiment of the present invention. With reference to FIG. 1, thecomputer system comprises a processor unit 100 that operates underprogram control, an I/O controller 110, a memory 120, and an I/O bus130. The I/O controller 110 may be a general-purpose I/O controller suchas a SCSI controller and a LAN controller.

[0026] The processor unit 100 includes an I/O controller managementmeans 101, an I/O driver means 102, an I/O controller diagnostic means103, and a memory management means 104.

[0027] The I/O controller management means 101 manages the condition ofthe I/O controller 110. The I/O driver means 102 provides access to theI/O controller 110. The I/O controller diagnostic means 103 verifiesnormal operation of the I/O controller 110 preparatory for installingthe I/O controller 110. The memory management means 104 manages accessesto the memory 120 from all units or sections. The respective means aregenerally realized from the execution of a program by the processor.

[0028] In the following, a detailed description will be given of theoperation of the system according to the first embodiment of the presentinvention referring to FIGS. 1 and 2. When the processor unit 100 isactivated, the I/O controller diagnostic means 103 receives an I/Ocontroller diagnostic request set as part of the prescribed starting upprocess of the processor unit 100 (step S201 in FIG. 2). Subsequently,the I/O controller diagnostic means 103 sets the I/O controllermanagement means 101 in diagnostic mode (step S202). The I/O controllermanagement means 101 issues an I/O controller installing instruction tothe I/O driver means 102 (step S203).

[0029] The I/O driver means 102 first hunts a memory area for controloperation by the I/O controller 110 through the memory management means104 (step S204). Then, the I/O driver means 102 executes a prescribedpseudo-I/O instruction so that bidirectional access occurs between theI/O controller 110 and the memory 120 to use a part or block of thememory area for control operation hunted previously (step S205).

[0030] Next, the I/O driver means 102 judges whether a specific normalresponse to the pseudo-I/O instruction has been obtained (step S206).

[0031] If the normal response has been obtained (step S206/YES), the I/Odriver means 102 checks whether all the memory patterns are tried,namely, all the space in the memory area for control operation has beenused (step S207). If unused memory area remains (step S207/NO), the I/Odriver means 102 returns to the operation at step S205 and executes thesimilar pseudo-I/O instruction to use another part or block of thememory area for control operation.

[0032] The I/O driver means 102 repeats the procedure from step S205 toS207 for all the memory blocks of address space necessary for I/O busaccess verification.

[0033] If the normal response has not been obtained (step S206/NO), theI/O driver means 102 stops the instillation operation, and notifies theI/O controller diagnostic means 103 that there is a failure.

[0034] The memory 120 and I/O bus 130 are verified by the judgment onwhether the specific normal response to every pseudo-I/O instruction hasbeen obtained or not as is described above.

[0035] If the normalcy of the I/O bus 130 is verified, that is, thespecific normal response to every pseudo-I/O instruction has beenobtained (step S207/YES), the I/O driver means 102 carries out theinstallation operation (step S208), and notifies the I/O controllerdiagnostic means 103 of the operation result.

[0036] The I/O controller diagnostic means 103 judges whether or not theinstallation operation has been normally performed (step S209).

[0037] If the installation operation has been normally performed (stepS209/YES), the I/O controller diagnostic means 103 activates a microdiagnostic program stored in the I/O controller 110 (step S210), andindicates to the system maintainer the diagnostic result that the I/Ocontroller 110 has been installed by display or the like (step S211).After that the I/O controller diagnostic means 103 releases the I/Ocontroller management means 101 from the diagnostic mode (step S212).

[0038] On the other hand, if the installation operation has not beennormally performed (step S209/NO), the I/O controller diagnostic means103 indicates to the system maintainer the diagnostic result by displayor the like (step S211), and releases the I/O controller managementmeans 101 from the diagnostic mode (step S212).

[0039] In accordance with the first embodiment of the present invention,the normalcy of the I/O bus is verified when installing the I/Ocontroller as is described above. Consequently, it is possible to detectan I/O bus failure as well as checking address parity in advance of theinstallation of the I/O controller, thereby preventing a failure fromoccurring after the installation. Thus, the reliability of the systemcan be improved.

[0040] In the following, the second embodiment of the present inventionwill be described.

[0041]FIG. 3 is a block diagram showing the configuration of the mainpart of a preferred computer system for the application of the secondembodiment of the present invention. Referring to FIG. 3, the computersystem comprises a processor unit 300 that operates under programcontrol, a SCSI controller 310 as an I/O controller, disk storage units320A and 320B as slave units of the SCSI controller 310, a memory 330,and an I/O bus 340.

[0042] The processor unit 300 includes an I/O controller managementmeans 301, an I/O driver means 302, and a memory management means 303.

[0043] The I/O controller management means 301 sends an I/O controllerinstalling instruction to the I/O driver means 302 at a restart of theprocessor unit 300 or when the system maintainer gives an instruction toinstall an I/O controller. The memory management means 303 managesaccesses to the memory 330 from all units or sections.

[0044] Having received the I/O controller installing instruction as atrigger, the I/O driver means 302 executes an instruction so thataccesses occurs from the SCSI controller 310 to the memory 330 and viceversa to verify whether bidirectional access between the controller 310and the memory 330 can be normally gained (pre-installation check).

[0045] After obtaining the verification, the I/O driver means 302installs the SCSI controller 310, disk storage units 320A and 320B inthe system. Accordingly, it becomes possible for other controllers (notshown) to use the disk storage units 320A and 320B.

[0046] When a failure is detected by the pre-installation check, the I/Odriver means 302 notifies a host processor of the failure. Thus, thehost processor can specify or locate the unit with the failure.

[0047] In the following, a detailed description will be given of theoperation of the system according to the second embodiment of thepresent invention referring to FIGS. 3 and 4. At a start or restart ofthe system, the I/O controller management means 301 receives a SCSIcontroller installing instruction set as part of the prescribed startingup process of the processor unit 300 (step S401 in FIG. 4).Incidentally, the system maintainer may input the SCSI controllerinstalling instruction as needed while the system is in operation. TheI/O controller management means 301 receives the SCSI controllerinstalling instruction in this case as well, and conducts the sameoperations as follows.

[0048] Having received the SCSI controller installing instruction, theI/O controller management means 301 issues a SCSI controller installinginstruction to the I/O driver means 302 (step S402).

[0049] The I/O driver means 302 first hunts memory areas for the controloperation of the SCSI controller 310 and the disk storage units 320A and320B through the memory management means 303 (step S403). Then, the I/Odriver means 302 executes a pseudo-I/O instruction so that bidirectionalaccess occurs between the SCSI controller 310 and the memory 330 to usea part or block of the memory area for the control operation of the SCSIcontroller 310 hunted previously (step S404).

[0050] Next, the I/O driver means 302 checks whether all the space inthe memory area for control operation of the SCSI controller 310 hasbeen used (step S405). If unused memory area remains (step S405/NO), theI/O driver means 302 returns to the operation at step S404 and executesthe similar pseudo-I/O instruction to use another part or block of thememory area for control operation of the SCSI controller 310. The I/Odriver means 302 repeats this until all the memory address spacenecessary for I/O bus access verification has been used.

[0051] If all the space in the memory area for control operation of theSCSI controller 310 has been used (step S405/YES), the I/O driver means302 executes a pseudo-I/O instruction to use a part or block of thememory area for control operation of the disk storage units 320A and320B hunted previously (step S406).

[0052] Similarly, the I/O driver means 302 checks whether all the spacein the memory area for control operation of the disk storage units 320Aand 320B has been used (step S407). If unused memory area remains (stepS407/NO), the I/O driver means 302 returns to the operation at step S406and executes the similar pseudo-I/O instruction to use another part orblock of the memory area for control operation of the disk storage units320A and 320B. The I/O driver means 302 repeats this until all thememory address space for controlling the disk storage units 320A and320B necessary for I/O bus access verification has been used.

[0053] If all the space in the memory area for control operation of thedisk storage units 320A and 320B has been used (step S407/YES), the I/Odriver means 302 judges whether the specific normal response to everypseudo-I/O instruction has been obtained to verify the normalcy of theI/O bus 340 (step S408). If there is a failure, the failure can belocated and the unit concerned with the failure is found out on thisoccasion.

[0054] Following the operation of step S408, the I/O driver means 302installs the SCSI controller 310 in the system (step S409), and notifiesthe I/O controller management means 301 of the operation result.

[0055] The I/O controller management means 301 judges whether or not theinstallation operation has been normally performed (step S410).

[0056] If the installation operation has been normally performed (stepS410/YES), the I/O controller management means 301 sets the SCSIcontroller 310 in an installed mode (step S411). On the other hand, if afailure is found at step S408, or the installation operation has notbeen normally performed (step S410/NO), the I/O controller managementmeans 301 indicates an error message to notify the system maintainerthat maintenance is required for the SCSI controller 310 (step S412).

[0057] In accordance with the second embodiment of the presentinvention, the normalcy of the I/O bus is verified when installing theSCSI controller as is described above. Consequently, it is possible todetect an I/O bus failure as well as checking address parity in advanceof the installation of the SCSI controller, thereby preventing a failurefrom occurring after the installation. Thus, the reliability of thesystem can be improved.

[0058] Moreover, a pseudo-I/O instruction is intentionally conducted soas to let I/O bus failure occur if any and to know the unit concernedwith the failure. Thus, the unit that may have the failure can bespecified when installing units in slave/master relationships (e.g. SCSIcontroller and disk storage units).

[0059] Besides, with the conventional system that dose not verify thenormalcy of the I/O bus, in the case where a SCSI controller failure isdetected when a disk storage unit #B is additionally installed in theactive system in which the SCSI controller and a disk storage unit #Ahave been already installed, failure recovery is performed for the SCSIcontroller even when the disk storage unit #A is in use. Consequently,accessing to the disk storage unit #A is interrupted, which affects asoftware or program running on the system. However, according to thepresent invention, it is possible to avoid such inconvenience since theSCSI controller failure is detected when installed.

[0060] While the present invention has been described with reference tothe particular illustrative embodiments, it is not to be restricted bythe embodiments but only by the appended claims. It is to be appreciatedthat those skilled in the art can change or modify the embodimentwithout departing from the scope and spirit of the present invention.

What is claimed is:
 1. A failure detection method for detecting a failure at a time when installing an I/O controller in a computer system, comprising the steps of: executing an instruction which involves providing I/O bus access to a memory to be used by the I/O controller after installed; determining that there is no failure when predetermined results are obtained with the instruction; and installing the I/O controller in the system.
 2. A failure detection method for detecting a failure at a time when installing an I/O controller in a computer system, comprising the steps of: executing an instruction which involves providing I/O bus access to a memory to be used by the t/o controller after installed; determining that there is no failure when predetermined results are obtained with the instruction and installing the I/O controller in the system; and notifying a host processor that there is a failure in the I/O controller when predetermined results are not obtained with the instruction so that the host processor can specify the I/O controller with failure.
 3. A failure detection method for detecting a failure at a time when installing an I/O controller in a computer system, comprising the steps of: executing an instruction which involves providing I/O bus access to a memory to be used by the I/O controller after installed; determining that there is no failure when predetermined results are obtained with the instruction; installing the I/O controller in the system; executing a micro diagnostic program stored in the I/O controller; and setting the I/O controller in the system when it is verified that there is no failure by the micro diagnostic program.
 4. A failure detection method for detecting a failure at a time when installing an I/O controller in a computer system, comprising the steps of: executing an instruction which involves providing I/O bus access to a memory to be used by the I/O controller after installed; determining that there is no failure when predetermined results are obtained with the instruction and installing the I/O controller in the system; executing a micro diagnostic program stored in the I/O controller; setting the I/O controller in the system when it is verified that there is no failure by the micro diagnostic program; and notifying a host processor that there is a failure in the I/O controller when predetermined results are not obtained with the instruction so that the host processor can specify the I/O controller with failure.
 5. The failure detection method claimed in claim 1, wherein the I/O controller has slave/master relationships with a plurality of slave units, further comprising the steps of: detecting a failure in the respective slave units when installing the I/O controller; and when a failure is found in any of the slave units, notifying the host processor of the slave unit having the failure.
 6. The failure detection method claimed in claim 2, wherein the I/O controller has slave/master relationships with a plurality of slave units, further comprising the steps of: detecting a failure in the respective slave units when installing the I/O controller; and when a failure is found in any of the slave units, notifying the host processor of the slave unit having the failure.
 7. The failure detection method claimed in claim 3, wherein the I/O controller has slave/master relationships with a plurality of slave units, further comprising the steps of: detecting a failure in the respective slave units when installing the I/O controller; and when a failure is found in any of the slave units, notifying the host processor of the slave-unit having the failure.
 8. The failure detection method claimed in claim 4, wherein the I/O controller has slave/master relationships with a plurality of slave units, further comprising the steps of: detecting a failure in the respective slave units when installing the I/O controller; and when a failure is found in any of the slave units, notifying the host processor of the slave unit having the failure.
 9. The failure detection method claimed in claim 1, wherein the I/O controller has slave/master relationships with a plurality of slave units, further comprising the steps of: executing an instruction which involves providing I/O bus access to a memory to be used by the respective slave units after installed; determining that there is no failure when predetermined results are obtained with the instruction; and notifying the host processor of the slave unit having a failure when predetermined results are not obtained with the instruction.
 10. The failure detection method claimed in claim 2, wherein the I/O controller has slave/master relationships with a plurality of slave units, further comprising the steps of: executing an instruction which involves providing I/O bus access to a memory to be used by the respective slave units after installed; determining that there is no failure when predetermined results are obtained with the instruction; and notifying the host processor of the slave unit having a failure when predetermined results are not obtained with the instruction.
 11. The failure detection method claimed in claim 3, wherein the I/O controller has slave/master relationships with a plurality of slave units, further comprising the steps of: executing an instruction which involves providing I/O bus access to a memory to be used by the respective slave units after installed; determining that there is no failure when predetermined results are obtained with the instruction; and notifying the host processor of the slave unit having a failure when predetermined results are not obtained with the instruction.
 12. The failure detection method claimed in claim 4, wherein the I/O controller has slave/master relationships with a plurality of slave units, further comprising the steps of: executing an instruction which involves providing I/O bus access to a memory to be used by the respective slave units after installed; determining that there is no failure when predetermined results are obtained with the instruction; and notifying the host processor of the slave unit having a failure when predetermined results are not obtained with the instruction.
 13. A failure detection method for detecting a failure at a time when installing an SCSI controller as an I/O controller in a computer system, comprising the steps of: executing an instruction which involves providing I/O bus access to a memory to be used by the SCSI controller after installed; determining that there is no failure when predetermined results are obtained with the instruction; and installing the SCSI controller in the system.
 14. A failure detection method for detecting a failure at a time when installing an SCSI controller as an I/O controller in a computer system, comprising the steps of: executing an instruction which involves providing I/O bus access to a memory to be used by the SCSI controller after installed; determining that there is no failure when predetermined results are obtained with the instruction and installing the SCSI controller in the system; and notifying a host processor that there is a failure in the SCSI controller when predetermined results are not obtained with the instruction so that the host processor can specify the SCSI controller with failure.
 15. A failure detection method for detecting a failure at a time when installing an SCSI controller as an I/O controller in a computer system, comprising the steps of: executing an instruction which involves providing I/O bus access to a memory to be used by the SCSI controller after installed; determining that there is no failure when predetermined results are obtained with the instruction; installing the SCSI controller in the system; executing a micro diagnostic program stored in the SCSI controller; and setting the SCSI controller in the system when it is verified that there is no failure by the micro diagnostic program.
 16. A failure detection method for detecting a failure at a time when installing an SCSI controller as an I/O controller in a computer system, comprising the steps of: executing an instruction which involves providing I/O bus access to a memory to be used by the SCSI controller after installed; determining that there is no failure when predetermined results are obtained with the instruction and installing the SCSI controller in the system; executing a micro diagnostic program stored in the SCSI controller; setting the SCSI controller in the system when it is verified that there is no failure by the micro diagnostic program; and notifying a host processor that there is a failure in the SCSI controller when predetermined results are not obtained with the instruction so that the host processor can specify the SCSI controller with failure.
 17. The failure detection method claimed in claim 13, wherein the SCSI controller has slave/master relationships with a plurality of slave units, further comprising the steps of: detecting a failure in the respective slave units when installing the SCSI controller; and when a failure is found in any of the slave units, notifying the host processor of the slave unit having the failure.
 18. The failure detection method claimed in claim 14, wherein the SCSI controller has slave/master relationships with a plurality of slave units, further comprising the steps of: detecting a failure in the respective slave units when installing the SCSI controller; and when a failure is found in any of the slave units, notifying the host processor of the slave unit having the failure.
 19. The failure detection method claimed in claim 15, wherein the SCSI controller has slave/master relationships with a plurality of slave units, further comprising the steps of: detecting a failure in the respective slave units when installing the SCSI controller; and when a failure is found in any of the slave units, notifying the host processor of the slave unit having the failure.
 20. The failure detection method claimed in claim 16, wherein the SCSI controller has slave/master relationships with a plurality of slave units, further comprising the steps of: detecting a failure in the respective slave units when installing the SCSI controller; and when a failure is found in any of the slave units, notifying the host processor of the slave unit having the failure.
 21. The failure detection method claimed in claim 13, wherein the SCSI controller has slave/master relationships with a plurality of slave units, further comprising the steps of: executing an instruction which involves providing I/O bus access to a memory to be used by the respective slave units after installed; determining that there is no failure when predetermined results are obtained with the instruction; and notifying the host processor of the slave unit having a failure when predetermined results are not obtained with the instruction.
 22. The failure detection method claimed in claim 14, wherein the SCSI controller has slave/master relationships with a plurality of slave units, further comprising the steps of: executing an instruction which involves providing I/O bus access to a memory to be used by the respective slave units after installed; determining that there is no failure when predetermined results are obtained with the instruction; and notifying the host processor of the slave unit having a failure when predetermined results are not obtained with the instruction.
 23. The failure detection method claimed in claim 15, wherein the SCSI controller has slave/master relationships with a plurality of slave units, further comprising the steps of: executing an instruction which involves providing I/O bus access to a memory to be used by the respective slave units after installed; determining that there is no failure when predetermined results are obtained with the instruction; and notifying the host processor of the slave unit having a failure when predetermined results are not obtained with the instruction.
 24. The failure detection method claimed in claim 16, wherein the SCSI controller has slave/master relationships with a plurality of slave units, further comprising the steps of: executing an instruction which involves providing I/O bus access to a memory to be used by the respective slave units after installed; determining that there is no failure when predetermined results are obtained with the instruction; and notifying the host processor of the slave unit having a failure when predetermined results are not obtained with the instruction.
 25. The failure detection method claimed in claim 1, further comprising the steps of informing a system maintainer as to the result of the installation of the I/O controller.
 26. The failure detection method claimed in claim 2, further comprising the steps of informing a system maintainer as to the result of the installation of the I/O controller.
 27. The failure detection method claimed in claim 3, further comprising the steps of informing a system maintainer as to the result of the installation of the I/O controller.
 28. The failure detection method claimed in claim 4, further comprising the steps of informing a system maintainer as to the result of the installation of the I/O controller.
 29. The failure detection method claimed in claim 5, further comprising the steps of informing a system maintainer as to the result of the installation of the I/O controller.
 30. The failure detection method claimed in claim 6, further comprising the steps of informing a system maintainer as to the result of the installation of the I/O controller.
 31. The failure detection method claimed in claim 7, further comprising the steps of informing a system maintainer as to the result of the installation of the 1/O controller.
 32. The failure detection method claimed in claim 8, further comprising the steps of informing a system maintainer as to the result of the installation of the I/O controller.
 33. The failure detection method claimed in claim 9, further comprising the steps of informing a system maintainer as to the result of the installation of the I/O controller.
 34. The failure detection method claimed in claim 10, further comprising the steps of informing a system maintainer as to the result of the installation of the I/O controller.
 35. The failure detection method claimed in claim 11, further comprising the steps of informing a system maintainer as to the result of the installation of the I/O controller.
 36. The failure detection method claimed in claim 12, further comprising the steps of informing a system maintainer as to the result of the installation of the I/O controller.
 37. The failure detection method claimed in claim 13, further comprising the steps of informing a system maintainer as to the result of the installation of the SCSI controller.
 38. The failure detection method claimed in claim 14, further comprising the steps of informing a system maintainer as to the result of the installation of the SCSI controller.
 39. The failure detection method claimed in claim 15, further comprising the steps of informing a system maintainer as to the result of the installation of the SCSI controller.
 40. The failure detection method claimed in claim 16, further comprising the steps of informing a system maintainer as to the result of the installation of the SCSI controller.
 41. The failure detection method claimed in claim 17, further comprising the steps of informing a system maintainer as to the result of the installation of the SCSI controller.
 42. The failure detection method claimed in claim 18, further comprising the steps of informing a system maintainer as to the result of the installation of the SCSI controller.
 43. The failure detection method claimed in claim 19, further comprising the steps of informing a system maintainer as to the result of the installation of the SCSI controller.
 44. The failure detection method claimed in claim 20, further comprising the steps of informing a system maintainer as to the result of the installation of the SCSI controller.
 45. The failure detection method claimed in claim 21, further comprising the steps of informing a system maintainer as to the result of the installation of the SCSI controller.
 46. The failure detection method claimed in claim 22, further comprising the steps of informing a system maintainer as to the result of the installation of the SCSI controller.
 47. The failure detection method claimed in claim 23, further comprising the steps of informing a system maintainer as to the result of the installation of the SCSI controller.
 48. The failure detection method claimed in claim 24, further comprising the steps of informing a system maintainer as to the result of the installation of the SCSI controller. 